Fixing device and image forming apparatus incorporating same

Abstract

A fixing device includes a first rotator, a second rotator, a heater, a conductor, and a discharger. The first rotator includes a conductive first layer, a non-conductive second layer, and a conductive third layer. The first to third layers exist in an order of the first layer to the third layer from a center of the first rotator to an outside of the first rotator. The second rotator forms a nip between the first rotator and the second rotator. A recording medium bearing a toner image passes through the nip. The heater is disposed inside a loop of the second rotator and heats the second rotator. The conductor is in contact with one of the first layer and the third layer. The discharger is in contact with the conductor and the other one of the first layer and the third layer and removes electric charge from the first rotator.

What is claimed is: 
     
       1. A fixing device comprising:
 a first rotator including:
 a first layer being electrically conductive; 
 a second layer not being electrically conductive; and 
 a third layer being electrically conductive; 
 the first layer, the second layer, and the third layer existing in an order of the first layer, the second layer, and the third layer from a center of the first rotator to an outside of the first rotator; 
 
 a second rotator forming a nip between the first rotator and the second rotator, the nip through which a recording medium bearing a toner image passes; 
 a heater disposed inside a loop of the second rotator and configured to heat the second rotator; 
 a conductor being in contact with one of the first layer and the third layer; and 
 a discharger being in contact with the conductor and the other one of the first layer and the third layer, the discharger configured to remove electric charge from the first rotator. 
 
     
     
       2. The fixing device according to  claim 1 ,
 wherein the conductor is in contact with the third layer and has a contacted portion to be brought into contact with the discharger, and 
 wherein the contacted portion is in a region from an outer surface of the third layer to an outer surface of the first layer in a radial direction of the first rotator. 
 
     
     
       3. The fixing device according to  claim 2 ,
 wherein the first layer has an exposed portion having an outer surface exposed to an outside of the first rotator, 
 wherein the exposed portion includes a first exposed portion and a second exposed portion, and 
 wherein the first exposed portion is in contact with the discharger and longer than the second exposed portion in the radial direction of the first rotator. 
 
     
     
       4. The fixing device according to  claim 3 ,
 wherein a position of an outer surface of the first exposed portion in the radial direction of the first rotator is same as a position of the contacted portion of the conductor in the radial direction. 
 
     
     
       5. The fixing device according to  claim 1 ,
 wherein the conductor is in contact with the first layer and has a contacted portion to be brought into contact with the discharger, and 
 wherein the contacted portion is outside an outer surface of the first layer in a radial direction of the first rotator. 
 
     
     
       6. The fixing device according to  claim 5 ,
 wherein the contacted portion of the conductor and at least one of an outer surface of the third layer or a surface of the second rotator are at a same position in the radial direction. 
 
     
     
       7. The fixing device according to  claim 1 ,
 wherein the conductor is in contact with the first layer, and 
 wherein an outer diameter of the conductor is smaller than an outer diameter of the first rotator. 
 
     
     
       8. The fixing device according to  claim 7 ,
 wherein the conductor is not in contact with the second rotator. 
 
     
     
       9. The fixing device according to  claim 1 ,
 wherein the conductor is in contact with the first layer, 
 wherein the conductor has lengths in a radial direction of the first rotator that are different in a circumferential direction of the first rotator, and 
 wherein the conductor is configured to come into contact with the second rotator in a partial region in the circumferential direction. 
 
     
     
       10. The fixing device according to  claim 1 ,
 wherein the conductor is in contact with the first layer, and 
 wherein a contact area in which the conductor contacts an end of the first rotator in an axial direction of the first rotator is equal to or less than one third of an area of a cross section of the first rotator, the cross section being orthogonal to the axial direction of the first rotator. 
 
     
     
       11. The fixing device according to  claim 1 ,
 wherein the conductor is in contact with the first layer, and 
 wherein the conductor includes a plurality of projections in contact with the first rotator, the plurality of projections projecting in an axial direction of the first rotator. 
 
     
     
       12. The fixing device according to  claim 1 ,
 wherein the conductor is made of an elastic material. 
 
     
     
       13. The fixing device according to  claim 1 , further comprising
 a connector configured to supply power to the heater and disposed opposite the conductor with respect to a center of the fixing device in a longitudinal direction of the fixing device. 
 
     
     
       14. The fixing device according to  claim 1 , further comprising
 a thermal conduction member on the heater, 
 wherein the discharger is in contact with the thermal conduction member. 
 
     
     
       15. The fixing device according to  claim 14 ,
 wherein the thermal conduction member includes graphene. 
 
     
     
       16. An image forming apparatus comprising the fixing device according to  claim 1 . 
     
     
       17. A fixing device comprising:
 a first rotator including:
 a first layer being electrically conductive; 
 a second layer not being electrically conductive; and 
 a third layer being electrically conductive; 
 the first layer, the second layer, and the third layer existing in an order of the first layer, the second layer, and the third layer from a center of the first rotator to an outside of the first rotator; 
 
 a second rotator forming a nip between the first rotator and the second rotator, the nip through which a recording medium bearing a toner image passes; 
 a heater disposed inside a loop of the second rotator and configured to heat the second rotator; 
 a conductor being in contact with the first layer; and 
 a discharger being in contact with the conductor and a surface layer of the second rotator, the discharger configured to remove electric charge from the first rotator. 
 
     
     
       18. An image forming apparatus comprising the fixing device according to  claim 17 . 
     
     
       19. A fixing device comprising:
 a first rotator including:
 a first layer being electrically conductive; 
 a second layer not being electrically conductive; and 
 a third layer being electrically conductive; 
 the first layer, the second layer, and the third layer existing in an order of the first layer, the second layer, and the third layer from a center of the first rotator to an outside of the first rotator; 
 
 a second rotator forming a nip between the first rotator and the second rotator, the nip through which a recording medium bearing a toner image passes; 
 a heater disposed inside a loop of the second rotator and configured to heat the second rotator; 
 a conductor being in contact with the first layer and the third layer; and 
 a discharger being in contact with at least one of the first layer, the third layer, the conductor, or a surface layer of the second rotator. 
 
     
     
       20. An image forming apparatus comprising the fixing device according to  claim 19 .